1. Field of the Invention
The present invention relates generally to a finishing tool for gears, and more particularly to a gear shaving cutter, which is rotated in meshing engagement with a gear material to be finished, so as to impart a shaving finish to the gear material.
2. Description of the Prior Art
In the case where a gear material to be finished is to be subjected to shaving or to cold or hot finish rolling, the gear material and a gear finishing tool, which may be, for example, a shaving cutter, are brought into firm meshing engagement with each other with an intersecting angle defined between both axes thereof for performance of the shaving operation, a zero degree angle being so defined for the performance of a cold rolling operation, such that one of the elements is forcibly driven while the other one thereof follows the rotation of the former, thus establishing the desired finishing operation.
In the case where shaving is to be accomplished by means of the use of a conventional shaving cutter, especially wherein a gear is to be shaved with a small intersecting angle defined between the axes of the shaving cutter and the gear to be shaved, as in the case of a shoulder gear, an excessively large contact area exists between the shaving cutter and the gear, or more specifically, between the land portions, which are formed upon the cutting faces of the teeth of the shaving cutter, and the faces of the gear. As a result, the contact pressure developed at the contacting faces of the elements is so reduced that even when a predetermined infeed face is imparted to the shaving cutter, the cutting edges of the land portions do not cut sufficiently into the face surface of the gear, the amount of shaving capable of being performed within one operation being substantially reduced, while at the same time, the time period required for accomplishing a predetermined amount of shaving is correspondingly lengthened. Therefore, the productivity of the shaving process is accordingly reduced.
If, on the other hand, the working pressure to be applied to the shaving cutter is so increased as to obtain the desired amount of cutting, elastic deformation is caused within the mandrel supporting the gear or within the gear itself, and as a result, the precision of the finishing operation of the face of the gear is greatly deteriorated.
In the case of cold rolling working, a finishing tool has been proposed which has the same shape as that of the shaving cutter and which has cutting teeth each of which is formed upon its entire face with grooves which are arranged equidistantly from the addendum to the deddendum so as to thereby define land portions therebetween. In this case, however, where the rolling working is accomplished by use of such a finishing tool with the contact pressure being non-uniform at the contacting faces of the finishing tool and the gear, wave marks are resultantly formed upon the flank of the finished gear, thus causing a considerable reduction in the precision working of the gear elements.